1. Field of the Invention
The invention relates to a walking beam furnace, the hearth of which consists, at least partially, of longitudinal beams arranged side by side and alternately formed as fixed beams and walking beams, and in which furnace each walking beam can be lifted and lowered by means of lifting rollers which can be moved on ramps.
2. Description of the Prior Art
Repair and maintenance operations on the walking beams and fixed beams of such a walking beam furnace, as is known, for example, from German Pat. No. 1,280,269, can frequently be performed without having to dismantle the walking beams, since the latter are at least partially accessible from above and below. However, in the case of other repair and maintenance operations it is necessary to dismantle the walking beams. This is necessary not only in the event of repairs on the walking beams themselves, but also if the fixed beams have to be reached from the side. These areas are generally inaccessible, even if the walking beams are in their upper or lower working position. Moreover, furnaces of this type possess sand-troughs or water-troughs to seal off the furnace interior from the atmosphere, which are located under the walking beams and are accordingly characterised by very poor accessibility. A walking beam furnace with two systems of mutually parallel walking beams, movable both longitudinally and vertically, is known from Austrian Pat. No. 230,279, in which a walking beam of one system is always adjacent to a walking beam of the other system. The arrangement is here designed in such a way that the walking beams of the two systems push the material to be annealed forward in alternation. To achieve this, the mutually independent drive-mechanisms for lifting and lowering each system and for displacing it in a straight line both in and opposite to the transport direction are coupled together in such a manner that one drive depresses one system below the transport plane and then lifts it again into the transport plane, while the other drive displaces the other system in opposition to the transport direction. The same repair difficulties also exist in the case of this walking beam furnace, as have been cited above with respect to the walking beam furnace known from German Pat. No. 1,280,269.